@article{01533622,
title = {Levelling an unknotting tunnel.},
journal = {Geometry \& Topology},
volume = {4},
year = {2000},
pages = {243-275},
doi = {10.2140/gt.2000.4.243},
zbl = {0958.57007},
language = {en},
url = {http://dml.mathdoc.fr/item/01533622}
}
Goda, Hiroshi; Scharlemann, Martin; Thompson, Abigail. Levelling an unknotting tunnel.. Geometry & Topology, Tome 4 (2000) pp. 243-275. doi : 10.2140/gt.2000.4.243. http://gdmltest.u-ga.fr/item/01533622/